Field of the Invention
The present invention relates to a spiral membrane element capable of separating specified components that are present in various fluids (liquid or gas), in which a separation membrane, a feed-side channel material, and a permeate-side channel material in a laminated state are wound in a spiral form around a center tube having a hole, as well as to a method of producing the same.
Description of the Background Art
Conventionally, as a fluid separating element used in reverse osmosis filtration, microfiltration, or the like, there is known a spiral membrane element provided with a cylindrical wound body R in which a separation membrane 1, a feed-side channel material 2, and a permeate-side channel material 3 in a laminated state are wound in a spiral form around a center tube 5 having a hole, where sealing parts 11 to 13 are disposed for preventing feed-side fluid and permeate-side fluid from being mixed with each other, for example, as shown in FIG. 6.
In this spiral membrane element, the feed-side fluid (feed water) is led to the surface of the separation membrane 1 by the feed-side channel material 2 and, after being separated by being transmitted through the separation membrane 1, the permeate-side fluid (permeate water) is led to the center tube 5 (water collection tube) along the permeate-side channel material 3. Further, in some cases in such a spiral membrane element, a fiber reinforced resin (FRP) may be disposed on an outer circumference as an outer cladding layer for the purpose of imparting the pressure resistance and the shape retaining property at the time of operation in a pressurized state.
As shown in FIGS. 7(a) and 7(b), such a spiral membrane element is generally produced by stacking a permeate-side channel material 3 onto a material obtained by disposing a feed-side channel material between two leaves of a two-folded separation membrane 1, applying adhesives 4, 6 on the permeate-side channel material 3 located on the separation membrane peripheral parts (three sides) so as to form sealing parts for preventing the feed-side fluid and the permeate-side fluid from being nixed with each other thereby to fabricate a separation membrane unit U, winding a single unit or a plurality of these units in a spiral form around the center tube 5, and further sealing the separation membrane peripheral parts. In this example, a plurality of membrane leaves (sealed envelope-shaped membranes) are present; however, there are cases in which a single membrane leaf is present.
Also, for forming the outer cladding material, there is known a method of winding polypropylene fibers impregnated with epoxy resin (in other examples, heat-resistant alkali plastic material fibers) around the outer circumferential surface of the cylindrical wound body after winding the membrane leaves around the center tube, followed by curing this to form the outer cladding material as a fiber-reinforced resin (FRP) (See Japanese Patent Application Laid-Open (JP-A) No. 2000-354742, FIG. 3, Paragraph No. 0037). Also, there is known a method of winding a net-shaped substance (heat-resistant alkali plastic material) having a cylindrical shape or a planar shape, and being embedded (curing to support) with an epoxy resin (See JP-A No. 2000-354742, FIGS. 4 and 5, Paragraph Nos. 0038 and 0039).
Also, as a method of forming an outer cladding layer, there is known a method of winding glass fibers on the outer circumferential surface of the cylindrical wound body, and further disposing an epoxy resin layer for protection of the glass fibers exposed to the surface after being embedded with an epoxy resin (See Japanese Patent Application Laid-Open (JP-A) No. 2001-17840, claim 1, FIG. 1).